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Wed Jul 23, 2014 4:57 pm

Hey guys, my old mechanical regulator finally bit the dust and I'm replacing it with a newer solid state one. The only thing I cant figure out is where the to attach the ground wire on the newer regulator. I've been looking around and it looks like some have suggested its not needed, but that makes me very nervous. Anyone have any direction?

Wed Jul 23, 2014 5:14 pm

It doesn't have a 3 prong plug on it?

Wed Jul 23, 2014 5:23 pm

if it is the goofy looking flat one sold as a replacement, be careful. for whatever reason, i have seen 3 generators cook to death. do a search, it seems to be a problem

Wed Jul 23, 2014 7:32 pm

I have a Bosch solid state regulator in my '65 Beetle, been running it over a year with zero problems. I did replace the generator at the same time, only because I got a lifetime warranty one from Advance Auto for like $30. And they had it in stock.

Wed Jul 23, 2014 8:46 pm

Its the Bosch Mexican one,

http://www.ebay.com/sch/sis.html?_nkw=14V+30Amp+Vo...0668278645

I grounded out the brown wire coming off of the generator to the body of the regulator and the frame of the bus.

Wed Jul 23, 2014 11:49 pm

You do need to ground the regulator to the generator. This makes sure it senses the actual generator output voltage (e.g. big red wire to brown wire). This (supposedly) eliminates any voltage drops in the ground circuit (specifically, the transmission ground strap) from affecting the generator output voltage. That's the way it's supposed to work, anyhow. Unfortunately, with a regulator grounded to the body, there may be a fistfight between the brown wire and the tranny ground strap, so make sure it's in good shape.

I'm assuming you have an upright engine bus, as 72 and later had a mating plug on the regulator. Only early bays had individual wire terminals.

The terminals on the regulator should be labeled, so match up the terminal labels to this:

By the way, using one of these regulators on a '71 with a 38 amp generator will derate it to 30 amps. May not be a big deal unless you have a need for those extra 8 amps...

Thu Jul 24, 2014 7:10 am

This new regulator does not have a ground specified. I'm thinking maybe I should slide the ground wire underneath this bolt?

Thu Jul 24, 2014 8:46 am

Not knowing what those two topside screws are attached to, I'd connect the ground wire to one of the unit mounting screws, such that it contacts the support leg.

Note: it appears from the picture that the D+ lug (the one with the nut and lock washer) is connected directly to the outer shell. If this is true, then the shell is at battery voltage when the generator is operating. Be careful to not let anything touch it and short it to ground...

[Picture found online]

I suspect that the actual regulator is in the small box on the bottom. The upper shell is likely isolating diodes which isolate the generator from the battery when the engine is stopped.

[Picture found online]

Thu Jul 24, 2014 10:22 am

telford dorr wrote: Note: it appears from the picture that the D+ lug (the one with the nut and lock washer) is connected directly to the outer shell. If this is true, then the shell is at battery voltage when the generator is operating. Be careful to not let anything touch it and short it to ground...

If the shell is at battery voltage as it appears, then that thing would be horribly dangerous and I sure wouldn't want it in my engine compartment. That think is a wiring harness melt down and fire waiting to happen. :cry:

Thu Jul 24, 2014 10:28 am

I'm fairly sure the shell is live on those but I think it's generator output opposed to battery voltage, either way be careful nothing touches it.